Technical Field of the Invention
The present invention relates to a liquid treatment apparatus that performs predetermined processes to a substrate such as a cleaning process and an etching process, by supplying a treatment liquid to the substrate while rotating the substrate held in a horizontal position.
Description of Related Art
In a semiconductor device manufacturing process, a resist film having a predetermined pattern is formed on a process target film which is formed on a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”), and the process target film is subjected to a process such as etching or ion implantation using the resist film as a mask. After the process, the unnecessary resist film is removed from the wafer.
A SPM treatment is typically used as a method for removing the resist film. The SPM treatment is performed by supplying the resist film with heated SPM solution (sulfuric acid hydrogen peroxide mixture) obtained by mixing sulfuric acid and hydrogen peroxide.
A device for performing a series of liquid treatments including the SPM treatment to a wafer is described in JP-A-2007-035866 (Patent Document 1). The device described therein includes: a spin chuck that rotates the wafer while holding the wafer in a horizontal position; a nozzle that supplies treatment liquids such as SPM solution and a rinse liquid (deionized water) to the wafer; and a splash guard (hereinafter referred to as “cup” in this specification) that receives a treatment liquid scattered radially outward from the upper surface of the wafer due to centrifugal force. Generally, since the SPM solution heated at a high temperature is discharged toward the wafer, the SPM treatment generates a fume comprising vapor and mist of the SPM solution and reactive products generated by the reaction of the SPM solution with a resist.
The device described in Patent Document 1 has a shielding plate (hereinafter also referred to as “top plate” in this specification) in order to prevent the fume from diffusing and contaminating the inside of a treatment chamber. During the SPM treatment, the shielding plate is placed near but above the wafer, while the shielding plate is not rotated.
The fume unavoidably adheres to a lower surface (surface facing the wafer) of the top plate. If condensed liquid droplets of the fume drop onto the wafer, the liquid droplets will contaminate the wafer. In order to avoid this, the top plate is cleaned every time the treatment to each wafer is completed. The device described in Patent Document 1 cleans the top plate by allowing a nozzle, dedicated to cleaning, to spray a cleaning liquid (for example, deionized water) to the lower surface of the top plate while rotating the top plate. Since the device described in Patent Document 1, however, does not have any parts radially outwardly of the top plate, it is probable that the fume components-dissolved cleaning liquid scatters into a space outside the cup and contaminates the inside of the treatment chamber.